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LM3150 - Power MOSFET problem

Unknown Unknown8
Prodigy 110 points
Other Parts Discussed in Thread: LM3150, CSD17302Q5A

Hello,

 i used Webbench to create a schematic for the LM3150 DCDC-converter. (The Webbench File and the schematic are attached.)
Input: 24Volt ;   Output: ~7V /   1 - 10 Ampere variable

Now I got a problem with two boards. On this boards the Powerfet M1  (CSD17302Q5A) broken while power-on. The resistance of M1 is now less then 1Ohm an the output voltage = input voltage.
In the Power on moment the output current was less then 0.5Ampere.

After I replaced the Powerfet M1 the boards are working. But how long??

Do you have any ideas why the FET's are broken?

Thanks

Matthias

3302.WebenchReportsServlet.pdf

 

  

  • 0
    TI__Genius 11085 points

    Matthias,

    The first thing I would check is that you have a long pair of leads from your power supply to the board or not. Since Webench did not add an electroletic cap at the input port, long leads would cause Vin ringing or large spikes at power up. Since M1 is rated at 30V, ringing at 24V input voltage could easily go beyond it and damage the FET.

    If it is the case, shorten input port leads, add a ~100uF electroletic cap at the input side, or use a higher voltage rating FET should help.

    regards,

    Yang

  • 0 in reply to YangZhang
    Prodigy 110 points

    Thanks for your help.

    I checked the Vin (24V) and while switch on the LM3150 there is a spike  about 30-37V.

    An 47uF electroletic cap is at the input side close to the DCDC-Converter. Now I will use a higher voltage rating FET.

     

    Thanks